Television receivers and recorders having a commercial detecting function for distinguishing television programs and commercials (also called “commercial messages”) are known.
Most of these apparatuses detect a commercial using a difference in audio states of a program and the commercial.
For example, Japanese Patent Unexamined Publication No. 5-250762 discloses the following.
Whereas sound used in a commercial is stereo sound, monophonic or multiplexed bilingual sound may be used in a program. In the document described above, the commercial is detected by detecting this difference in the sounds.
Japanese Patent Unexamined Publication No. 2003-47031 discloses the following.
A commercial is detected by detecting a silent state of sound at the time of switching of a program and the commercial. Japanese Patent Unexamined Publication No. 2003-47031 further discloses a method of judging whether a broadcast is a program and detecting a commercial by detecting an interval during which a silent state between the program and the commercial occurs.
Japanese Patent Unexamined Publication No. 11-136634 discloses the following.
In a program broadcasted with a movie as a material, a signal converted from the movie into a television signal, i.e., a signal of a telecine video and a normal television signal are discriminated. Consequently, a commercial created by the normal television signal and the program are distinguished.